Dittrichia viscosa y Rubus ulmifolius como reservorios de parasitoides de áfidos
The role of the self-sown shrubs Dittrichia viscosa (L.) W. Greuter and Rubus ulmifolius Schott as reservoirs of aphid parasitoids was investigated. In the field studies conducted, D. viscosa grew adjacent to crops of durum wheat and barley and R. ulmifolius grew adjacent to cotton. The relative abundance of the parasitoids of (a) Capitophorus inulae (Passerini) on D. viscosa, (b) Rhopalosiphum padi (Linnaeus) on durum wheat and barley, (c) Aphis ruborum (B¨orner) on R. ulmifolius, and (d) Aphis gossypii Glover on cotton in various parts of Greece, was assessed during the years 1996–2000. In 2000, the fluctuation of parasitization of the above four aphid species was recorded and the action of the aphidophagous predators of the family Coccinellidae was studied. It was observed that Aphidius matricariae Haliday predominated on C. inulae and R. padi in all sampling cases. In contrast, Lysiphlebus fabarum (Marshall) was the dominant species parasitizing A. ruborum on R. ulmifolius and A. gossypii on cotton in Thessaly (central Greece) and Macedonia (northern Greece), whereas Lysiphlebus confusus Tremblay et Eady and Binodoxys acalephae (Marshall) were the dominant parasitoid species in Thrace (northern Greece). Coccinella septempunctata Linnaeus was the most abundant coccinellid species on durum wheat, whereas Adonia variegata (Goeze) predominated on cotton. However, coccinellid individuals were scarce on both D. viscosa and R. ulmifolius. The present study indicated that these two shrubs can be regarded as useful reservoirs of aphid parasitoids.